U.S. Pat. No. 4,575,305 to Krajicek et al. relates to a truck mounted tube bundle pulling apparatus. In this invention the tube bundle pulling apparatus is attached to a telescoping column. The telescoping column is rotatably mounted to the rear of the bed. Although this invention is commercially successful it has one primary disadvantage. The apparatus exceeds the legal highway weight limits and therefore requires permitting for street travel.
The highway legal limits are 34,000 lbs. on the dual drive axles, and 12,000 lbs. per steering axle. The invention disclosed in the '305 patent resulted in a weight of approximately 42,000 lbs. on the rear axles and 10,000 lbs. on the steer axle. This distribution could not be remedied due to the fixed location of the mass on the bed of the truck. For the past several years, Serv-Tech has spent many thousands of dollars in highway permits for transporting what has been classified as an overweight vehicle. Serv-Tech has also spent many thousands of dollars in unseen costs on equipment and manpower waiting for permits, waiting on weather conditions since many states will not permit movement during bad weather and storing and housing equipment and manpower since many states will not permit movement of overweight vehicles during nights, weekends and holidays.
Several unsuccessful attempts were made to resolve this problem. For example, an attempt was made to redistribute the weight by adding a third rear axle. This did not work and only exacerbated the steering problems.
At the time application for the '305 patent was made the weight distribution or highway legal problem was not recognized and therefore, at the time, there could not have been any motivation to solve the problem. Once the problem was recognized it took several unsuccessful attempts to resolve the problem before Applicant conceived of shifting the mass between two positions to resolve the problem.